Preheat your oven to 325 degrees Fahrenheit and position the rack in the lower third of the oven. Grease your loaf pan or bundt pan thoroughly with butter or cooking spray, then dust it with flour and tap out the excess.

In a medium bowl, whisk together the flour, baking soda, and salt until fully combined.

In a large bowl with an electric mixer, beat the room-temperature butter and sugar together for 3 to 4 minutes until the mixture is pale, light, and fluffy. Stop occasionally to scrape down the bowl sides.

Add the eggs to the butter mixture one at a time, beating well after each addition until the previous egg is fully incorporated.

Beginning and ending with the flour mixture, alternate adding the dry ingredients and sour cream to the batter in three additions of flour and two additions of sour cream. Start with about one-third of the flour, then half the sour cream, then another third of flour, then the remaining sour cream, and finally the last of the flour. Mix on low speed, just until each addition is combined.

Stir in the vanilla extract and lemon zest (if using) with a wooden spoon or rubber spatula, mixing gently until just combined.

Pour the batter into your prepared pan and use an offset spatula or the back of a spoon to smooth the top. Tap the pan gently on the counter a few times to release any air bubbles.

Bake for 50 to 55 minutes, until the top is golden brown and a toothpick inserted into the center comes out with just a few moist crumbs clinging to it. Don't open the oven door in the first 40 minutes. If the top is browning too quickly, loosely tent it with foil for the remaining bake time.

Let the cake cool in the pan for 15 minutes before running a thin knife around the edges and turning it out onto a wire rack. Let cool completely before serving.